Established pyrotechnic mixtures for the production of bang-effects and/or flash effects are, e.g., black powder, mixtures of potassium perchlorate with metal powders, or mixtures of barium nitrate with metal powders optionally with the addition of sulfur. The use of barium peroxide-based pyrotechnic mixtures for the production of bang-effects and/or flash effects in military applications no longer meets the requirements due to the lack of handling safety in the extended temperature range. The same also applies to mixtures based on potassium chlorate.
To produce high sound pressure performances in so-called “flash-bang” grenades, particularly effective mixtures of potassium perchlorate with metal powders such as aluminum, magnesium or alloys thereof, are suitable. In addition to a high performance level, these mixtures excel in their handling safety and storage stability. The temperature stability and low water solubility of the potassium perchlorate used as oxidizing agent is, i.a., responsible for this.
Due to ecotoxicological and human toxicological concerns against the use of perchlorate-containing compounds, in the meantime, on the part of the personnel, there are requirements for appropriately perchlorate-free applications with performance characteristics that remain the same as perchlorate-containing applications as far as possible. As a rule, the simple substitution of perchlorate-containing pyrotechnic mixtures by those based on a nitrate of alkali metals, or alkaline-earth metals, leads with the given design to distinct performance losses, at least unless another performance-raising additive is used. Against the background of limiting guidelines with respect to weight, geometry and freedom from fragments of the respective applications, a fulfillment of the more recent requirements can only be expected via a combined solution comprising new pyrotechnic mixtures combined with designs specific thereto.
With U.S. Pat. No. 7,578,895 A, perchlorate-free flash-bang mixtures were suggested for use in pyrotechnic practice ammunition, including their production-methods and mixing methods. These flash-bang mixtures are composed of 45.0%, by weight, to 60.0%, by weight, potassium nitrate as oxidizing agent, 0.5% by weight to 1.5% by weight boric acid as pH stabilizer, 0.2% by weight to 0.8% by weight of an anti-baking agent, preferably silicon dioxide, 35.0% by weight to 45.0% by weight aluminum powder as metallic combustible material, 5.0% by weight to 10.0% by weight of a nonmetallic combustible material, preferably sulfur, approx. 0.5% by weight carbon or graphite and 0% by weight to 10.0% by weight of a “ballistic accelerator” such as black powder, cellulose nitrate, or a commercially available single-base or double-base propellant powder. Some of the test results relating to U.S. Pat. No. 7,578,895 A were presented by the inventors at the International Pyrotechnic Symposium 2006 for mixtures with potassium nitrate as well as with strontium nitrate.
During this same event, another group of United States scientists published research on performance-raising additives that have been known for a long time, or on known perchlorate-based mixture systems that are postulated to be components of this type (c.f., Comparison of Output and Sensitivity of Various Flash Compositions Commonly Used in Pyrotechnics; Joseph E. May, Jr.; Joseph A. Domanico; International Pyrotechnic Symposium, 2006, Fort Collins, CO, USA). In addition to the peak pressure performance and sound performance, the shock sensitivity of various powder mixtures was ascertained quantitatively in comparison with a standard mixture of 70%, by weight, potassium perchlorate and 30%, by weight, aluminum powder.
The partial substitution of the metallic fuel, in this case aluminum, by up to approx. 10% by weight sulfur or a sulfur-containing, sulfidic inorganic compound, as far as the peak pressure performance is concerned, leads to a rise in performance with simultaneous increase of the shock sensitivity. Since for some armed forces the use of sulfur or sulfidic inorganic compounds is forbidden in flash-bang applications, in the scope of the present invention, the use of sulfur or corresponding sulfur-containing compounds was deliberately omitted.
The partial replacement of a classic flash-bang mixture by a gas-forming, pyrotechnic component/a “ballistic accelerator” (black powder, nitrocellulose or propellant powder) can lead to a rise in performance as far as the peak pressures to be attained are concerned. As a rule, a simultaneous increase in the shock sensitivity is again observed thereby. With a replacement of approx. more than one third of the original classical flash-bang mixture observed here, a drop in performance is observed with respect to the peak pressure.
The variation of the quality of the aluminum used, as well as its replacement by another metallic fuel of different qualities, can lead to increases in performance in some cases even without a rise in the shock sensitivity, but here, in the case of magnesium, for example, it must be taken into consideration that this cannot be used automatically in military applications without a corresponding surface treatment or a coating to increase the stability of the mixture. An appropriate surface treatment, or a coating, leads, as a rule, to mixtures whose performance is poorer, possibly even with an increase in the shock sensitivity (chromatized magnesium).
The object, and thus the aim, of the present invention is the preparation of novel perchlorate-free, powdery pyrotechnic mixture systems that, used in pyrotechnic objects and/or ammunition, serve to produce bang effects and/or flash effects.